著者

松田 昇一 加藤 純郎 秋葉 貴光

出版者

一般社団法人 日本機械学会

雑誌

年次大会 2020 (ISSN:24242667)

巻号頁・発行日

pp.S05406, 2020 (Released:2021-03-25)

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Impingement jets are often used for cooling and heating of a surface or a body because a high heat transfer coefficient is obtained near the stagnation point of an impingement surface. For example, they are used for drying paper and fabrics, cooling gas turbine blades and electronic components(1). Recently, the usage of impingement jets can be predicted to be used in comparatively small spaces due to the miniaturization of devices. In these cases, the nozzle diameter, the flow rate, and the distance between the nozzle and the impingement plate are inevitably small.The purpose of this study is to clarify the flow and heat transfer characteristics when an impingement jet is applied in a narrow space. And now, when the heat transfer coefficients are measured by using the thin heated surface, a heat loss (qe) occurs in the in-plane direction of the heated surface due to heat conduction. Generally, this heat loss is often ignored at high Reynolds number (Re) and large diameter, because it is very small compared to the heat taken by the impingement jet. However, it may not be negligible in the case of a low Reynolds number and small diameter, because the heat taken by the impingement jet become relatively small.In this research, heat transfer characteristics using a circular impinging jet, which impinge on the heated plate, were investigated experimentally. The jet holes with the diameters D of 1, 3 and 5 mm were used. The values of H/D were from 2 to 6, where H is the distance between the nozzle exit and the impingement plate. The experiments were performed with the relatively low Reynolds number range of 250 ~ 2500. The surface temperature of the impingement plate was measured using an infrared camera, from which a heat loss (qe) in the in-plane direction and heat transfer coefficients were obtained. And the flow behavior of the jet was visualized by using a Laser Light Sheet(LLS)method. From the experiments, it was found that a heat loss (qe) needs to be considered in the case of a low Reynolds number and a small diameter.

著者

松田 昇一 棚原 靖 田中 学

出版者

一般社団法人 溶接学会

雑誌

溶接学会全国大会講演概要

巻号頁・発行日

vol.2021, pp.8-9, 2021

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ガスメタルアーク(GMA)溶接は,一般に溶着速度が速く,溶込みが深い高能率な溶接法である.しかしながら電極が溶融することから,熱源が時間的・空間的に変動し,アークが不安定になる.そのためスパッタが発生しやすくなり,溶接欠陥が生じやすい.本研究の目的は,交流磁場を用いた新しい高品質・高効率なGMA溶接法の開発である.本報では交流磁場がアークおよびビード形状に与える影響を報告する.

著者

松田 昇一 棚原 靖 田中 学

出版者

一般社団法人 溶接学会

雑誌

溶接学会全国大会講演概要

巻号頁・発行日

vol.2020, pp.18-19, 2020

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ガスメタルアーク(GMA)溶接は,一般に溶着速度が速く,溶込みが深い高能率な溶接法である.しかしながら電極が溶融することから,熱源が時間的・空間的に変動し,アークが不安定になる.そのためスパッタが発生しやすくなり,溶接欠陥が生じやすい.そこで我々は,外部磁場(直流または交流)を用いてGMA溶接のアークの安定化を試みた.本研究では外部磁場がアーク形状およびビード形状に与える影響を報告する.

著者

中山 友裕 松田 昇一 棚原 靖

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会九州支部講演論文集

巻号頁・発行日

vol.2019, 2019

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<p>TIG welding is one of the welding methods widely used in industries for high reliability of joints, little occurrence of spattering and high convenience of construction. However, compared with other arc welding methods, there is a disadvantage that depth of penetration is sallow. To solve this problem, the authors propose a new ECMP (Electromagnetic Controlled Molten Pool Welding Process) method which controls the molten metal flow by using electromagnetic forces generated in the molten pool by a magnetic field perpendicular to the unidirectional current.</p><p>Incidentally, although the conventional ECMP method has mostly prevented the molten metal from sagging downward by using an upward electromagnetic force, the authors propose the use of a downward electromagnetic force in this study. When the direction of the magnetic field is reversed from the conventional method, in principle it is possible to obtain a downward electromagnetic force in the direction of gravity. Utilizing the downward electromagnetic force, improvement of the weld penetration in the TIG welding process of thick plates can be anticipated.</p><p>In this paper, the authors describe in detail their investigation of the influence of the generated downward electromagnetic force on the molten pool flow, the molten pool surface temperature, and the final bead shape when using the new ECMP method which forcefully uses such a downward electromagnetic force.</p>

著者

松田 昇一 棚原 靖 田中 学 中山 友裕

出版者

一般社団法人 溶接学会

雑誌

溶接学会全国大会講演概要

巻号頁・発行日

vol.2018, pp.374-375, 2018

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TIG溶接は溶接面の欠陥発生が少なく,耐食性や靱性に優れているが,溶け込みが浅い欠点がある.そこで我々は,外部磁場を用いてTIG溶接の溶け込み制御を試みた.本研究では外部磁場が溶融池の流れおよびビード形状におよぼす影響を報告する.

著者

米須 清一郎 松田 昇一 加藤 純郎

出版者

一般社団法人 日本機械学会

雑誌

年次大会

巻号頁・発行日

vol.2017, 2017

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<p>Impingement jets are often used for the cooling and heating of a surface or a body because a high heat transfer coefficient is obtained near the stagnation point of an impingement surface. Recently, as equipment becomes smaller, impingement jets have been utilized in narrow spaces. In such a case, the nozzle diameters and Reynolds number which based on the nozzle exit velocity also become tinier as a matter of course. Generally, in the case of measuring the heat transfer coefficient by using a thin heat transfer surface, heat loss, <i>q</i>_e due to heat conduction in the in-plane direction in the heating surface occurs. However, <i>q</i>_e has been considered inconsequential in the case of the common impinging jets having large diameters and with large Reynolds number. However, <i>q</i>_e may not be negligible in the case of impinging jets having a small diameter and with low Reynolds number. In this research, heat transfer characteristics using rows of impinging jets with small diameters and with low Reynolds number were investigated experimentally. The jet holes with the diameters <i>D</i> of 1, 2 and 3 mm were used. The experiments were performed with the relatively low Reynolds number range of 170~1460. The surface temperature of the impingement plate was measured using an infrared camera, from which heat transfer coefficients on the surface were obtained. It was found that the <i>q</i>_e needs to be considered in the case of impinging jets having small diameters and with low Reynolds number.</p>

著者

親川 兼勇 屋我 実 那須 謙一 瀬名波 出 松田 昇一 安座間 工

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.63, no.607, pp.979-985, 1997-03-25

被引用文献数

4

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Heat transfer characteristics and flow patterns were measured over the plate for various separation distances between the nozzle exit and target plate when the air issuing from a sharpedged cross-shaped nozzle impinges on the plate. The local heat transfer coefficients in the radial direction for different circumferential positions were calculated using the wall temperatures measured by means of thermocouples, and the flow patterns were observed using a oil-titanium IV oxide method. The isotherms of the infrared images were also measured using an infrared radiometer with a two-dimensional array of InSb sensors. The geometric axes were switched due to the self-induced velocity of a vortex filament ; the convex corners became flat and the concave corners generated outward ejection. The distribution of the iso-heat-transfer-coefficient contours corresponds well to the flow pattern and the isotherm contours. These contours extended diagonally and demonstrated the Andrew's cross pattern for the short separations, subsequently becoming the octagonal patten, and then becoming circular at large separations. The correspondence of the heat transfer characteristic to the flow behaviors, and the heat transfer mechanism were also described.

著者

松田 昇一 Ishiuchi Toru 親川 兼勇

出版者

沖縄工業高等専門学校

雑誌

独立行政法人国立高等専門学校機構沖縄工業高等専門学校紀要 (ISSN:1881722X)

巻号頁・発行日

vol.3, pp.67-76, 2009-03

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衝突噴流群は広範囲に大きな熱伝達率が得られることから,ガスタービン翼の冷却および燃焼室の冷却など工業的に広く利用されている.高温鋼板やシートの冷却では,大きな熱伝達率が必要と同時に一様に冷却することも重要となる.しかしながら衝突噴流群の流れ場は,隣接する噴流同士の干渉や,壁面に衝突後外部へ流出する流れとの干渉により複雑となっており,場所によっては,熱伝達率値に大きな差異がみられる.また最近の機器の小型化に伴い,衝突噴流群も狭い空間内で使用される.その場合,衝突噴流群の流れ場は隣接する壁面の影響により,さらに複雑な流れ場となり,温度場も複雑となる.本研究では,比較的狭い空間内において衝突噴流群を垂直に高温壁に衝突させた場合の流れ場と高温壁面上の温度分布を測定し,流れ場が温度場に及ぼす影響を明らかにすることを目的としている.流れ場は,噴口上流部より煙を流入させ,噴口と衝突平板間に側面よりシート光(レーザ)を入射し可視化を行った.煙の粒子径は約1μm であり,レーザーは出力が1000mW のグリーンレーザである.温度場は,衝突平板裏面より赤外線放射温度計を用いて測定を行った.赤外線放射温度計には256×236のインジウムアンチモンセンサーが搭載されており,伝熱面全面の温度分布を同時に測定することができる.空間分解能は本実験条件において0.3×0.3mm であり,フレーム速度は1/120fps である.これらの実験結果より,衝突噴流群を垂直に高温壁に衝突させた場合の流れ場が温度場に与える影響を明らかにし,幾つかの実験式を提案した.